Previous compositional and immunological studies have defined the chemical and antigenic structure of the group-specific carbohydrate for Groups A, A variant and C streptococci. These polysaccharides were shown to have a common core structure. Work is in progress to determine the structure of the group specific carbohydrate of the Group B streptococcus in order to chemically define its antigenic determinants and to determine its chemical relationship to the other streptococcal group specific carbohydrates. Structural determination of an antigenic polysaccharide isolated from eggs of Schistosoma mansonii is under investigation using GCMS techniques. Lipoteichoic acid from Staphylococcus aureus was isolated by hot phenol extraction. Amino acid analysis and GCMS methods have yielded data concerning the amino acid composition, fatty acid profile, and carbohydrate composition of this preparation.